Part Type
Aluminum Fixture Plates & Workholding
Flat, drilled on grid, and dead repeatable.
An aluminum fixture plate is a flat plate drilled on a grid of tapped and dowel holes so it locates and clamps a part the same way every cycle, as a sub-plate or bolted to your part. Cast tooling plate (MIC-6 or Alca) is stress-relieved so it stays flat, and the dowel holes get reamed to a tight class so parts repeat within thousandths. Send a STEP file and a PDF through the quote form for a quote in 24-48 hours, with no minimum order. Plates are the workholding end of the custom fixtures index, which covers check, weld, assembly and test fixtures built to print.
Updated September 2026
What a fixture plate actually is
At its simplest a fixture plate is a flat slab of aluminum with a pattern of holes in it: tapped holes on a grid for clamps and toe stops, reamed dowel holes for repeatable location, and counterbored slots where bolts pass through to the part underneath. A sub-plate is the version that bolts to the machine table and gives you a clean tapped grid to build off, so you stop drilling into the table itself. A locating fixture goes further and holds one specific part: edge stops, pins, and clamps positioned so the operator drops the part in one way and it sits the same way every time.
The whole point is repeatability. When a part loads against two reamed dowel pins and a flat datum face, it lands in the same spot every cycle, so the program stays true and parts come off interchangeable. Plates are quoted build to print: send the grid, the dowel class and the flatness you need on the drawing, and if any of that is missing the quote lists it rather than deciding on your behalf.
Flatness and material: cast tooling plate vs 6061
Material choice comes down to how flat the plate has to stay. Cast aluminum tooling plate (MIC-6, Alca, or generic cast tool plate) is pre-stress-relieved, so it arrives flat and stays flat after the holes go in, which is what you want in a sub-plate or a precision locating fixture. General-purpose 6061 is the right call for everyday fixtures and anything where a few thousandths of bow will not hurt, and it costs less and takes anodize cleanly.
When flatness or parallelism has to be held to a real number, the plate gets precision ground after machining: blanchard or surface grinding flattens the working face and brings two faces parallel. That is the move for plates that mate to a granite surface, register against a machine table, or stack with other tooling where error adds up. Call out the flatness you need and it gets ground to suit.
The features that make it repeatable
The features that earn their keep are the ones that control location and clamping. Reamed dowel holes are the big one: held to a tight class (think ±0.0005 in) so a hardened dowel pin presses to a slip fit and the plate registers without slop. The tapped grid sets your clamping options: a common pitch is 1 in or 2 in centers in 1/4-20 or 3/8-16, which lines up with off-the-shelf clamps, toe stops, and strap kits. Counterbored clamp slots let you slide and lock hold-downs anywhere along a line.
Edge stops and locating pins set where the part sits, and how the plate gets clamped (vises, soft jaws cut to the part profile, or a vacuum fixture for thin work) sets how it holds. A vacuum plate suits sheet, gaskets, and parts too thin to clamp without bowing. Most of this runs through CNC milling, where the grid, pockets, and dowel bores all get cut in one setup so they stay true to each other.
Soft jaws: the vise version of the same idea
Soft jaws are aluminum or mild steel vise jaws machined to the shape of one part, so a casting, a round or an awkward profile clamps on a real surface instead of on two hard lines. They are cut in place on the machine that will use them, which is what makes them repeat: the pocket is bored from the same coordinates the program runs in, so a part seated in the jaw is already located. Serrated, stepped and dovetailed jaw forms all get made to print.
What the drawing has to carry is the vise: make and jaw width, the mounting hole pattern and its fit, jaw blank thickness, and the part profile with the clamp depth and the amount of part that must stand proud. Aluminum jaws suit finished and soft parts and are quick to recut; mild steel suits a heavy cut or a jaw that gets reused across many jobs. Say which and how many sets, because jaws are usually ordered in pairs and often several pairs at once.
Tombstone plates and multi-face tooling
A tombstone is the column on a horizontal machining centre that presents several faces of work to the spindle, and the plates that bolt to it are the same job as a sub-plate with one extra constraint: every face has to be square and parallel to the others, because a part on face one and a part on face three are cut in the same program. So the callouts that matter are perpendicularity between faces, parallelism across each face, and the position of the locating dowels relative to the tombstone pattern.
Those plates are quoted from your print with the tombstone bolt pattern, the grid pitch and thread size, the dowel class and the flatness and squareness numbers stated. Pallet and tombstone sets are quoted together so every plate is made from the same setup and interchanges. Where a part-specific nest bolts to the plate rather than being cut into it, machined nests covers that half.
Build to your print, and what the quote asks for
Send the STEP and a PDF that calls out the dowel-hole class, the tapped grid pitch and thread size, any flatness or parallelism requirement, the plate material, and the machine table or tombstone pattern it bolts to. That is a build-to-print quote in 24-48 hours. If the fixture drawing does not exist yet, send the part model and print with the clamped and located faces marked plus a dimensioned sketch, and the quote lists what is still missing before a build-to-print number can be given. No drawing yet? Fixture design is quoted as its own line. Send the part, the features to locate and check, and how it’s loaded. This is everyday work for custom machinery builders.
Replacing a plate you already own works the same way. A one-off plate can be reverse engineered from a new sample part into a clean model and remade, with any change you specify on the new print. The sample ships back with the parts. One plate or a matched set for a cell, with no minimum. Plates are the workholding corner of the custom machined fixtures range, which covers check, CMM, weld, assembly, test and masking fixtures built to print.
Questions
Before you send a job.
01 What is the difference between a tooling plate and a 6061 plate?
Cast tooling plate (MIC-6, Alca) is pre-stress-relieved, so it arrives flat and stays flat after machining, which matters for sub-plates and precision locating fixtures. 6061 is the general-purpose pick for everyday fixtures where a little bow is fine, and it costs less and anodizes well. State the flatness the plate has to hold on the drawing and the material follows from that number.
02 How tight can you hold the dowel holes for repeatable location?
Reamed dowel holes are held to a tight class, around ±0.0005 in, so a hardened dowel pin presses to a slip fit and the plate registers without slop. That is what makes a part land in the same spot every cycle. General dimensions on the plate run to ±0.005 in, since only the locating features need the tight numbers.
03 Can you hold a flatness number on the plate?
Yes. When flatness or parallelism has to hit a real spec, the plate is precision ground after machining: blanchard or surface grinding flattens the working face and brings two faces parallel. Call out the flatness on the print and it gets ground to suit. As-milled is fine when no tight number is required.
04 I have a part but no fixture drawing. Can you still quote it?
Send the part model and print with the clamped and located faces marked, plus a dimensioned sketch of the plate you have in mind, and the quote lists what is still missing before a build-to-print number can be given. If you would rather have the plate designed from the part, fixture design is quoted as its own line. With a model and a print it is cut to print in the usual way.
05 Do you make soft jaws?
Yes, in aluminum or mild steel, machined to one part profile. The drawing needs the vise make and jaw width, the mounting hole pattern and its fit, the jaw blank thickness, and the part profile with clamp depth and how much part must stand proud. Jaws are usually ordered in pairs, and several pairs are quoted as one order.
06 Can you make tombstone or pallet plates?
Yes, from your print. The callouts that matter are perpendicularity between faces, parallelism across each face, the grid pitch and thread size, the dowel class, and the tombstone or pallet bolt pattern, because a part on one face and a part on another are cut in the same program. Sets are quoted together so every plate is made from the same setup and interchanges.
07 Can you copy or improve a fixture plate I already own?
Yes. A one-off plate can be reverse engineered from a new sample part into a clean model and remade, with any change you specify on the new print (different dowel spacing, a deeper clamp slot, a tighter flatness callout). One replacement plate or a matched set for a cell both work, with no minimum order.
Related
Where to go next.
CNC Milling
Where the grid, pockets, and dowel bores get cut in one setup.
View →Precision Grinding
For plates that have to hold a real flatness number.
View →Custom Machined Fixtures
Check, CMM, weld, assembly, test and masking fixtures.
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